1. Field of the Invention
The present invention relates to a clip device for holding a living tissue, which is inserted into a living body through an endoscope channel, and used to stop bleeding and to mark a part to be medically treated.
2. Description of the Related Art
A known clip device is generally inserted into a
living body through an endoscope channel, and left in a cavity of a living body in the state clipping a living tissue, for example, a mucus membrane in the cavity and a blood vessel.
This type of clip device is disclosed by Jpn. Pat, Appln. KOKAI Publication No. 4-102450 (patent document 1), for example. This application discloses a device which comprising a clip unit 1 shown in FIGS. 8A and 8B, and a clip control unit 2 shown in FIGS. 8C and 8D. The clip unit 1 is provided with a α-shaped clip 3, as shown in FIG. 8A. The clip 3 is made of thin metal plate (a part of clip) bent at the center, forming a substantially ring-like base ring 3a. Further, a pair of clip hands 3c extends almost straight from the base ring 3a, crossing each other at a point 3b. The clip 3 has the characteristic of expanding in the direction of separating the clip hands 3c. 
Further, this clip device has a plate-like connection member 4, a holder tube 5 for tightening a clip, and a hold member 6. The connection member 4 is engaged with the base ring 3a of the clip 3. The holder tube 5 is fit around the connection member 4, and has a diameter smaller than the base ring 3a. The hold member 6 is filled in the holder tube 5, and holds the connected part of the base ring 3a and connection member 4.
A substantially J-shaped hook (an engagement part) 4a is provided at the front end of the connection member 4, as shown in FIG. 8B. The hook 4a is engaged with the base ring 3a. The hold member 6 is made of filler such as silicone. An engagement hole 4b is provided in the base end of the connection member 4. The engagement hole 4b is engaged with a connection pin 7a of a hook unit 7 of the clip control unit 2 described later.
The grip control unit 2 consists of a slender insertion part 8 and a control unit 9 for connecting the close-to-hand side of the insertion part 8. The insertion part 8 has a lead-in tube 10, a control tube 11, and a control wire 12, as shown in FIG. 8C. The control tube 11 is inserted into the lead-in tube 10. The control wire 12 is inserted into the control tube 11. The hook unit 7 is provided at the front end of the control wire 12. The hook unit 7 has the pin 7a for connecting the connection member 4.
As shown in FIG. 8D, the control unit 9 has a tube coupler 13, a main control unit 14, and a slider unit 15. The tube coupler 13 is fixed to the close-to-hand side of the lead-in tube 10. The main control unit 14 moves the control tube 11 forward and rearward. The slider unit 15 moves the control wire 12 forward and rearward.
The clip unit 1 is fixed to the control unit 2, and led into a living body cavity, in the following six steps.
(1) Push the main control unit 14 of the clip control unit 2 toward the front end side, and project the control tube 11 from the lead-in tube 10.
(2) Push the slider unit 15 toward the front end side, and project the hook unit 7 from the control tube 11.
(3) Adjust the positions of the engagement hole 4b of the connection member 4 of the clip unit 1 and the pin 7a of the hook unit 7 of the clip control unit 2, and insert and engage the pin 7a into the engagement hole 4b. 
(4) Pull the slider unit 15 toward the base end side, and fit the holder tube 5 to the front end of the control tube 11.
(5) Pull the main control unit 14 toward the base end side, and house the clip unit 1 into the lead-in tube 10.
(6) Insert the insertion part 8 of the clip control unit 2 into a living body cavity through an endoscope channel.
Next, close the clip unit 1 in the following steps.
(1) Push the main control unit toward the front end side, and project the clip unit 1 from the lead-in tube 10.
(2) Pull the slider unit 15 a little toward the base end side, and extend the connection member 4 toward hand. By this operation, the base ring 3a is gradually pressed to fit into the holder tube 5, as shown in FIG. 9A. In this time, the base ring 3a pressed to fit into the holder tube 5 is gradually crushed, and deformed to have a smaller size (the diameter is reduced). At the same time, the clip hands 3c are deformed in the expanding direction, interlocking with the deformation of the base ring 3a, and expanded to the substantially maximum expanded position. While being held in the substantially maximum expanded state, the base ring 3a is completely inserted into the holder tube 5, as shown in FIG. 9B. In this state, let the clip 3 grip an object living tissue by the clip hands 3c. 
(3) Then, pull the slider unit 15 further toward the base end side. By this operation, the connection member 4 is extended to the side close to hand, and the base of the clip hands 3c is pressed to fit into the holder tube 5. By the extension of the connection member 4 in this time, the clip hands 3c are moved in the closing direction to clip the living tissue by the clip hands 3c, as shown in FIG. 9C.
Further, while the clip hands 3c are being closed as shown in FIG. 9C, pull the connection member 4 further to the side close to hand. By this operation, the substantially J-shaped hook 4a at the front end of the connection member 4 engaged with the base ring 3a is plastically deformed to the extended state, as shown in FIG. 10B. As a result, the base ring 3a and connection member 4 are disengaged, and the connection member 4 is separated from the base ring 3a. By this operation, the clip 3 is closed in being held by the holder tube 5, as shown in FIG. 9D.
FIG. 11 is a graph showing the changes in the force applied to the clip 3, when the slider unit 15 of the control unit 9 is pulled to the side close to hand when closing the clip 3. In FIG. 11, the point 0 indicates start of pulling the connection member 4, the point A indicates the time the base ring 3a is pressed to fit into the holder tube 5 as shown in FIG. 9A, the point B indicates the time the clip hands 3c of the opened clip 3 contact the holder tube 5 as shown in FIG. 9B, and the point C indicates the time the front ends of the clip hands 3c of the clip 3 contact each other and the clip hands close completely as shown in FIG. 9C. At the point A between 0 and B, the force of expanding the clip hands 3c becomes the maximum (force F1). In this time, the clip hands 3c are expanded to the substantially maximum expanded position. And, in the area between the points A and B, the clip hands 3c are held in the state expanded substantially maximum.
Further, in the states after the point B in FIG. 11, the clip hands 3c are moved in the closing direction by the extension of the connection member 4, and changed from the substantially maximum expanded state as shown in FIG. 9B, to the completely closed state as shown in FIG. 9C. At the point C, the force of closing the clip hands 3c is F2. In the state after the point C, the substantially J-shaped hook 4a at the front end of the connection member 4 engaged with the base ring 3a as shown in FIG. 10A, is switched to be plastically deformed to the extended state as shown in FIG. 10B. The point D indicates the time the engagement of the base ring 3a and connection member 4 is released, and the connection member 4 is separate from the base 3a, as shown in FIG. 10B.
When closing the clip unit 1 of the clip device configured as described above, pull the slider unit 15 of the control unit 9 toward the side close to hand, and pull the connection member 4. Then, expansions of the clip hands, clipping operation and disengaging operation succeed. To expand the clip hands, press the base ring 3a to fit into the holder tube 5, and expand the clip hands 3c. For the clipping operation, press the base of the clip hands 3c to fit into the holder tube 5, move the clip hands 3c in the closing direction, and let the clip hands 3c clip a living tissue. For the disengaging operation, deform plastically the substantially J-shaped hook 4a at the front end of the connection member engaged with the base ring 3a to the state of extending the hook 4a, and disengage the base ring 3a from connection member 4.